Prehistoric fire dynamics in the sagebrush habitat of the endangered Gunnison Sage Grouse

Authors: Jared Crain*, , Zachary P. Taylor, Berry College
Topics: Paleoenvironmental Change, Mountain Environments, Biogeography
Keywords: paleoenvironmental reconstruction, lake sediments, Gunnison Sage Grouse, fire, Colorado
Session Type: Poster
Day: 4/11/2018
Start / End Time: 3:20 PM / 5:00 PM
Room: Napoleon Foyer/Common St. Corridor, Sheraton, 3rd Floor
Presentation File: No File Uploaded

The Gunnison Sage Grouse (Centrocercus minimus), federally designated as a threatened species, is dependent on sagebrush for food and cover. The sagebrush shrub lands are maintained by fire. Here, we use a 2.58 m sediment core from Big Alkali Lake, Colorado (38°45'7.89"N, 106°55'39.40"W, 3,164 m) to reconstruct past fire dynamics and environmental history. Charcoal is less abundant in the upper 30 cm of the core, with the remainder of the record exhibiting several peaks in charcoal abundance, suggesting a fire regime with intermittent fires. We found herbaceous, woody, and lattice charcoal fragment types, with herbaceous charcoal making up the majority of particles. This suggested that most burned material came from non-woody vegetation. Loss on ignition analysis found that sediments are rich in organic content, varying from approximately 12% to 48% and that some peaks in charcoal correspond to peaks in organic content. In alpine environments such as Big Alkali Lake, organic content is a proxy for lake productivity, which is controlled by temperature, so our record suggests that fires are occurring during relatively warm periods. The core from Big Alkali Lake also contains several notable changes in stratigraphy. To better characterize these changes, we performed particle size analysis. The upper and lower 100 cm of the core have a greater amount of very fine sands, but the middle 70 cm has a higher percentage of clays and silts. Our record will be helpful to develop management efforts in the fire-dependent habitat of the Gunnison Sage Grouse.

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